Heroes emerge from Boston Marathon tragedy

(CNN) — “Moments like these, terrible as they are, don’t show our weakness; they show our strength.” These words were spoken by Suffolk County, Massachusetts, District Attorney Dan Conley after Monday’s terror attack in Boston.

A day later, signs of that strength are seen in the stories of people — you might call them heroes — who were near the Boston Marathon finish line when two bombs exploded seconds apart.

Carlos Arredondo’s story began nearly nine years ago, when he doused himself with gasoline and used a welder’s torch to set his body on fire. Arredondo, a Costa Rican immigrant living in Florida, had just been told his 20-year-old son, Marine Lance Cpl. Alexander Arredondo, was killed in combat in Iraq.

Arredondo initially thought the three Marines pulling up to his home were bringing…